1. Field of the Invention
The present invention is generally related to a system for inhibiting fouling of an underwater surface and, more particularly, to a system which is capable of self-calibration in order to select appropriate voltages and currents for its operation, to determine the type of water in which the surfaces are submerged, and to diagnose faults or damage in the underwater surfaces.
2. Description of the Prior Art
Many different systems are well known to those skilled in the art of inhibiting the fouling of underwater surfaces. Depending on the type of water in which the surfaces are submerged or partially submerged, the fouling can consist of algae, barnacles, zebra muscles, or other types of underwater organisms that tend to grow on and cling to submerged surfaces. The submerged surfaces can be portions of a hull of a marine vessel or other submerged components, such as grates for underwater conduits.
U.S. Pat. No. 948,355, which issued to Tatro et al. on Feb. 8, 1910, describes a system that provides anodes and cathodes on a ship and passes electric current through these two poles. The circuit is completed through seawater near the ship and chlorine is liberated. The chlorine kills the barnacles near the ship and prevents barnacles from fouling the submerged surface of the ship.
U.S. Pat. No. 1,021,734, which issued to Delius et al. on Mar. 26, 1912, is intended for use with a ship that has a metallic surface. An electric generator or other source of current is used and a switch is used to periodically change the circuit of an anode and a cathode which is completed through water surrounding the ship. Chlorine is produced and the fouling of the submerged surface of the ship is inhibited.
U.S. Pat. No. 3,625,852, which issued to Anderson on Dec. 7, 1971, describes a marine antifouling system. The antifouling system is intended for use with a boat or ship having a keel and sides diverging upwardly therefrom. A pair of laterally spaced elongated anode electrode components are mounted externally on one side of the hull substantially adjacent the keel and lengthwise thereof. An elongated cathode electrode component is mounted externally on the lengthwise of the keel in spaced relationship between the anode electrode components. A source of electric current energizes the anode electrode components with a positive potential and the cathode electrode component with a negative potential to produce various chemicals, such as chlorine, which inhibits fouling of the surface of the ship.
U.S. Pat. No. 6,173,669, which issued to Staerzl on Jan. 16, 2001, discloses an apparatus and method for inhibiting fouling of an underwater surface. Current is caused to flow through seawater in which two conductive surfaces are submerged or partially submerged. A monitor measures the current flowing from one of the two surfaces to the other in order to assure that no leakage of current of substantial quantity exists. By alternating current direction between the two surfaces, both surfaces can be provided with sufficient chlorine gas bubbles to prevent marine growth from attaching to the surfaces.
U.S. Pat. No. 6,209,472, which issued to Staerzl on Apr. 3, 2001, discloses an apparatus and method for inhibiting fouling of an underwater surface. The system provides an electric current generator which causes an electric current to flow proximate the underwater surface. A source of electric power causes a flow of current which passes from the underwater surface through water surrounding the surface or in contact with the surface. Gas is liberated from seawater and inhibits the growth of barnacles and other microorganisms on the submerged surfaces.
U.S. Pat. No. 6,547,952, which issued to Staerzl on Apr. 15, 2003, discloses a system for inhibiting fouling of an underwater surface. Ambient temperature cure glass (ATC glass) provides a covalent bond on an electrically conductive surface, such as nickel-bearing paint. In this way, boat hulls, submerged portions of outboard motors, and submerged portions of sterndrive systems can be protected effectively from the growth of marine organisms, such as barnacles. The protective coating of glass inhibits the migration of metal ions from the electrically conductive surface into the seawater and therefore inhibits corrosive degradation as a result of galvanic action.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
As marine surfaces, such as the surfaces of a boat hull, experience different conditions (e.g. a move from saltwater to freshwater or vice versa), it would be significantly beneficial if an automatic system could be provided to make appropriate adjustments in the operation of the antifouling system. In addition, it would be significantly beneficial if an automatic calibration system could be provided for this type of antifouling system. Furthermore, a system that could detect damage to an antifouling surface would provide a significant benefit to a system for preventing marine fouling of that surface.